The present invention relates to electrolytic processing device for belt-shaped metal plates. More particularly, the invention relates to an electrolytic processing device capable of electrolytically processing either one or both surfaces of a belt-shaped metal plate selectively.
In electrolytically processing the surface of a metal such as aluminum or iron, an electrolytic plating method, an electrolytic polishing method, an electrolytic etching method, an anodic oxidizing method, an electrolytic coloring method and a satin finish processing method have been extensively employed. Furthermore, a continuous electrolytic processing method is well known in the art in which such an electrolytic processing method is continuously applied to a belt-shaped metal plate.
FIG. 1 is an explanatory sectional view showing the fundamental construction of an electrolytic processing device in which the above-mentioned anodic oxidizing method is applied in a continuous manner to a belt-shaped aluminum plate. As shown in FIG. 1, a belt-shaped aluminum plate 1 is fed into a current feeding bath 2 guided by rolls 4. The bath 2 is filled with an electrically conductive electrolyte 3. The aluminum plate 1 is transported while being immersed in the electrolyte 3. A plurality of anode plates 5 connected to the positive terminal of an electric power source are arranged both sides of the path along which the aluminum plate 1 passes. Thus, the aluminum plate 1 acts as the cathode in the electrolyte in the bath 2.
The aluminum plate 1 is moved from the bath 2 into an electrolytic bath 6. The current feeding bath 2 is separated from the electrolytic bath 6 by a partition 7. The electrolytic bath 6 is filled with an electrolyte 8. A plurality of cathode plates 9 and 9' connected the negative terminal of the electric power source are arranged both sides of the path along which the aluminum plate 1 passes. Thus, the aluminum plate 1 acts as the anode in the electrolytic bath 6. As a result of electrolysis of the electrolyte 8, the surface of the aluminum plate 1 is oxidized and an oxide film is formed thereon. The aluminum plate 1 on the surface of which the oxide film has been formed as described above is delivered to the next processing stage where it is subjected to an after treatment as required.
Devices for electrolytically processing aluminum plates as described above have been disclosed in U.S. Pat. Nos. 3,038,850 and 3,471,375, Japanese Patent Publication Nos. 16530/1967 and 7842/1970 and Japanese Patent Application (OPI) (the term "OPI" as used herein refers to a "published unexamined Japanese Patent Application") No. 106927/1974. These devices are excellent for electrolytically processing both surfaces of a belt-shaped aluminum plate. However, they are nevertheless economically disadvantageous if it is desired to subject only one surface of the aluminum plate to electrolysis in that a film is unavoidably formed on both surfaces.
A device for subjecting only one surface of an aluminum plate to electrolysis has been disclosed in Japanese Patent Publication No. 8711/1961 and Japanese Patent Application (OPI) No. 29001/1972. In contrast with the above-described devices, these devices are inconvenient in the case where it is desired to electrically process both surfaces of an aluminum plate.
Devices which can process one or both surfaces of a metal plate have been proposed in Japanese Patent Publication Nos. 15287/1967 and 23127/1971. The device described in the former employs a system in which no electrode is provided on the side of a metal plate surface which should not be subjected to electrolytic process. Therefore, if it is desired to switch from a two-surface process to a single surface process, it is necessary to remove the electrodes provided on the side of the metal plate surface which should not be processed. Thus, this device is not very practical. On the other hand, the device described in the latter Publication employs a method in which no electrolyte is supplied to the side of a metal plate surface which should not be processed. However, that device has not found much practical use because the distance between the surface of a liquid film formed on the metal plate surface and the electrodes is variable so that the resultant film is not uniform.
Accordingly, a first object of the present invention is to provide an electrolytic processing device which can selectively electrolytically process either both surfaces or one surface of a belt-shaped metal plate.
A second object of the invention is to provide electrolytic processing device in which an electrolytic process for both surfaces of a belt-shaped metal plate and an electrolytic process for one surface of a belt-shaped metal plate can be readily and selectively employed.